1. Field of the Invention
This invention relates to optical systems, and more specifically, to an optical system incorporating a resonator to enhance the resolution of optical inspection systems and other optical devices that may include a low reflectivity surface as a surface of interest that lies within a path of resonance reflections in the resonator.
2. Description of the Related Art
Resonator-enhanced optical inspection systems, storage devices and other optical systems, such as those described by U.S. Pat. Nos. 6,653,649, 6,700,840, 6,714,295, 6,717,707, 6,778,307 issued to Applicant Clark and others, the specifications of which are incorporated herein by reference, provide improved resolution, surface detection and other performance improvements in traditional optical systems and provide new types of optical systems that were not available prior to the inventions disclosed therein.
In particular, the combination of a partially reflective surface with a surface under measurement to form a Fabry-Perot resonator provides increased resolution, improved differentiation of surface height and differentiation of surface characteristics, and improved feature detection over the prior available techniques.
However, when forming an optical resonator with a surface having a less than ideal reflectivity at a wavelength or wavelengths at which an optical measurement or detection is either desirable or otherwise dictated, the performance of the resonator is compromised by the reflectivity of the surface.
It would therefore be desirable to improve the performance of the resonator-enhanced optical systems disclosed in the above-referenced patents, as well as other resonator-enhanced optical systems when one of the resonator surface has a less than ideal reflectivity, in order to provide surface measurement or feature detection when the reflectivity of the surface is less than desired.